So I went off yonder for a few months, I'm a little late to the party. However, I am having this same issue (more or less) on my K55 running firmware v30.06. My CUE is up to date, along with Windows and all my other drivers. Unlike most people on this thread, I have a Scimitar Pro mouse. Before I disappeared, my K55 had a different issue (which still isn't fixed, rip) where when I pressed a macro key on my mouse (which are all bound to single keys on the keyboard) then that specific key would repeatedly spam faster than humanly possible. That issue is mostly fixed now, but it crops now and again (though not with keys bound to my mouse). The bigger problem is the random disconnects from my PC. Another problem is that the caps lock and num lock lights don't light up most of the time, so I can never tell if I'm in caps lock or num lock until I go to type. This problem has caused me problems logging into accounts, and even my PC in general.